1. Field of the Invention
The present invention relates to an improvement of a damping system for an offset press, and more particularly to a damping or humidifying system for an offset press in which the peripheral speed between the water-applicator roller and the plate cylinder are different thereby hicky and ghosts are prevented from occurring and thus printing performance is improved.
2. Description of the Prior Art
In a conventional damping system of this type for an offset press, it is known to slightly decrease a peripheral speed of a water-applicator roller relative to that of a plate cylinder so as to reduce hicky and ghosts. More particularly, in the conventional damping system for the offset press, the water-applicator roller is also driven through gears by a main motor which drive the offset press such that the peripheral speed of the water-application roller is lower than that of the plate cylinder by a predetermined amount. In this case, a problem so called "gear seam" is made on the surface of printed matter due to the play of the gears. Furthermore, since the ratio between the peripheral speed of the water-applicator roller and the plate cylinder is determined by the gear ratio, the speed difference cannot be changed at will. Therefore, when the rotational speed of the plate cylinder is lower than a desired value, the peripheral speed difference is small, and thus hicky removal is poor. On the other hand, when the rotational speed of the plate cylinder is higher than a desired value, the peripheral speed difference is large, and thus the wear on the plate increases to shorten the life thereof. Due to this problem, it is necessary to change the gear ratio by replacement of the gears in order to provide a large number of products.